Apparatus for draining off excess liquid from coated articles



June 5, 1956 F. WOMMELSDORF 2,743,746

APPARATUS FOR DRAINING OFF EXCESS LIQUID FROM COATED ARTICLE Filed March10, 1953 i 'gi K mnfly gn RC1 United States Patent APPARATUS FORDRAINING OFF EXCESS LIQUID FROM COATED ARTICLES Fritz Wommelsdorf,Hamburg-Rissen, Germany Application March 10, 1953, Serial No. 341,455 2Claims. (Cl. 118-57) This invention relates to improvements inimpregnating means for containers made of paper, cardboard, or the like,and is primarily directed to the provision of means for effectivelydraining off superfluous impregnating solution which adheres to thecontainer walls after they have been treated therewith by dipping orspraying.

Paper containers, such as drinking cups, shipping receptacles, and thelike, which are in extensive use today, are generally impregnated or areprovided with a surface coating of wax, plastics, lacquer and otherwateror fatrepelling masses for the purpose of preventing the contentsof such containers from penetrating into the paper walls. At the presenttime, impregnation is generally accomplished by mechanical means inseveral steps, whereby the containers to be impregnated are firstpreheated, then dipped in the impregnating solution or sprayedtherewith, then either dried or cooled, depending on the kind ofimpregnation applied. The chief aim in impregnating is to achieve thatthe impregnating agent enters into all pores and crevices of the paperwalls and covers the latter in a uniform, thin, uninterrupted film, butto avoid that excessive mass sticks to certain portions of the walls. Ithas been customary to let the containers, after they have been treatedwith the solution, pass a certain distance on a belt conveyor or thelike where superfluous material finds time to drain off before settingtakes place. Such draining-off method however does not give theassurance of uniform impregnation, because gravity alone acts too slowand only in one direction.

The object of this invention is to improve the present draining-01fmethod by providing acoustical vibrating means which set the containersinto vibrating motion while the same are passing through the drainingdistance. Such vibration effects that the surface tension of the stillliquid coating is more readily overcome, that particles of impregnatingcompound are forced into pores and crevices by their own inertia, andthat superfluous solution drains off considerably faster.

The practical construction of the present invention can take severalforms. The acoustic means for imparting the vibration to the containerstakes preferably the form of a diaphragm located above the passingcontainers and energized by electromagnets setting the diaphragm, thecolumn of air beneath, and therewith the containers in vibrating motion.The frequency of vibration is preferably regulated to approach thenatural frequency of the containers to be impregnated.

An embodiment of the invention is illustrated, by way of example, in theaccompanying drawing, in which Fig. 1 represents a side elevation of aconveyor carrying containers, generally indicated as drinking cups, forthe purpose of draining; and shows the acoustic vibrating means in theform of a diaphragm with actuating electromagnets; and

Fig. 2 is a plan top view of a fragmentary portion of the belt showingits perforations and the spacers which prevent the cups from shiftinglengthwise.

The endless-belt conveyor illustrated in Fig. 1 is assumed to bearranged as draining means in an impregnation setup. The containers,indicated as drinking cups 1, have just been coated with impregnatingsolution by dipping or "ice spraying (means for peforming this operationare not shown) and have been set, upside down, on the conveyor belt 2traveling on pulleys 3 in the direction of the arrow. After thecontainers have passed conveyor 2, they drop on a second conveyor belt 8traveling in opposite direction. This second conveyor preferablytraverses a zone in which setting of the impregnation is caused. It maybe a cooling zone, if wax or the like is the impregnating mass; or itmay be a drying zone, if lacquer serves as impregnation. At the otherend of the conveyor the finished containers drop into a storage bin 9.The conveyor belt, of which a fragmentary portion is shown as top viewin Fig. 2, is of perforated material, preferably wire screen, and isprovided with cross bars 10 in order to keep the containers spacedduring their vibratory motion.

The acoustic vibrating means indicated as a diaphragm 11, electromagnets12, and a supporting frame 13, are all arranged as a unit above theconveyor belt. The electromagnets, when energized by alternating currentfrom a source indicated at 14, will vibrate diaphragm 11, which in turnwill impart acoustic oscillation to the air column between diaphragm andconveyor belt and thus excite vibration in the containers lying on thebelt. Such vibration effects that the still liquid impregnating solutionadhering to the containers is forced into pores and crevices of thecontainer walls and that superfluous solution drains off considerablyfaster, leaving a uniform thin film evenly distributed over the entiresurface. This vibration by acoustic means is more efiicient thanmechanical action and has the additional advantage that no wear ofmechanical parts by friction is caused. The source of alternatingcurrent can be a 60 cycle power supply, but it is advantageous to employa source giving variable frequency, as indicated in the figure, so thata frequency can be selected which is most suitable for a certain case.The most efficient operation is with a frequency which correspondssubstantially to the natural frequency of the containers to be vibrated,and which may, in some cases, lie well within the lower portion of theultrasonic range. Instead of arranging a single vibratory diaphragm(loudspeaker) above the belt as indicated in the figure, it is obviousthat several such units can be placed along the conveyor.

The embodiment of the invention as illustrated and described is only anexample of a great number of possible constructions and othermodifications will occur to those skilled in the art. Therefore, I wishit to be understood that the example shown is not to be construed aslimiting to the invention as claimed in the appended claims.

What I claim is:

1. In an arrangement for impregnating paper containers or the like, adraining conveyor on which impregnated and still wet containers areplaced, acoustic vibrating means above said conveyor being effective insetting the air column beneath and therewith said containers invibratory motion to thereby accelerate the draining-off process.

2. An arrangement as in claim 1 wherein said acoustic vibrating meanscomprise a diaphragm, electromagnets adjacent to said diaphragm, and analternating current source for energizing said magnets, said alternatingcurrent source being of variable frequency for adjusting the vibratingtune of said diaphragm to the natural frequency of said containers.

References Cited in the file of this patent UNITED STATES PATENTS371,990 Stone Oct. 25, 1887 1,185,329 Janisch May 30, 1916 2,023,822Arnott et a1 Dec. 10, 1935

1. IN AN ARRANGEMENT FOR IMPREGNATING PAPER CONTAINERS OR THE LIKE, ADRAINING CONVEYOR ON WHICH IMPREGNATED AND STILL WET CONTAINERS AREPLACED, ACOUSTIC VIBRATING MEANS ABOVE SAID CONVEYOR BEING EFFECTIVE INSETTING THE AIR COLUMN BENEATH AND THEREWITH SAD CONTAINERS IN VIBRATORYMOTION TO THEREBY ACCELERATE THE DRAINING-OFF PROCESS.